A Miniaturized Magnetoelectric Wireless Power Transfer System with an Integrated DC Magnetic Bias

In this abstract, we present a miniaturized magnetoelectric wireless power transfer (MEWPT) system with a MEWPT receiving antenna and a spiral-coil-based transmitter. Four DC magnets are integrated onto the MEWPT receiving antenna to significantly reduce its overall dimension while providing a DC magnetic bias of 190 Oe for optimal performance. Electrochemical polarization characterizations are adopted to analyze the performance of the WPT receiving antenna, which reveal that maximum output power of 4.096 and 1.155 mW are obtained when the distance between the transmitter and receiving antenna are 0 and 0.5 cm, respectively, which corresponds to record energy conversion efficiency(ECE) of 2.64% and 0.654%, the highest among all MEWPT systems to date. The output power is improved by at least 49.3 times compared with the MEWPT system without integrated DC magnets. We demonstrate that the MEWPT system can power low power electronics, showing its potential applications in internet of things (IoT) and implantable medical devices (IMD).<br/><br/>Wireless power transfer (WPT) system, which transfers energy without a physical link, has received significant research interest. Due to the advantages of small dimension, low operation frequency and low transmission loss, MEWPT systems have been presented in the past few years as a promising technology. However, MEWPT systems require a DC magnetic bias for optimal performance and prior arts have implemented large electromagnets, Helmholtz coils or externally positioned magnet bias systems, which increases the system dimension. Furthermore, prior MEWPT studies report low energy conversion efficiency (ECE). In this paper, we report a miniaturized MEWPT system with an integrated DC magnetic bias, which significantly reduces the MEWPT system dimension. A 10-turn spiral coil is implemented as the WPT transmitter and a ferrite plate backplate is integrated on the spiral coil to enhance its transmitting performance. Electrochemical polarization characterizations, including the output voltage versus current characterization and output power versus current characterizations are adopted to systematically analyze the performance of the MEWPT receiving antenna. The equivalent internal resistance of the MEWPT receiving antenna is obtained by linearly fitting the output voltage versus current curve. The MEWPT receiving antenna shows an output power of 4.096 mW and 1.155 mW when the distance between the transmitter and receiving antenna is 0 cm and 0.5 cm, which corresponds to record ECE of 2.64% and 0.654% among all MEWPT systems to date. The equivalent internal resistance of the MEWPT receiving antenna is measured to be 5.04 kΩ when the output power is at 4.096 mW. We demonstrate that the MEWPT system can wirelessly power low power light emitting diodes and microchips at a distance of 0.5 cm, which demonstrates the potential applications in IoT and IMD. As the input voltage to the inductive coil transmitter decreases, the output voltage of the receiving antenna linearly decreases. The directivity and off-axis characteristics of the MEWPT receiving antenna are also measured, which shows that the directivity and off-axis distance have a significant impact on the MEWPT receiving antenna performance.